Some existing systems allow creation of virtual desktops using linked clones, such as with the View Composer feature in the Virtual Desktop Infrastructure (VDI) product by VMware, Inc. In such systems, the virtual desktops share a common base image residing on their parent VM's base disk but each virtual desktop has its own delta disk. This storage consolidation enables customers to reduce the storage cost for their virtual deployment. However, the size of the delta disk grows over time. This not only discounts the storage savings brought by the base disk consolidation, but also deteriorates the runtime disk access performance.
Some of the existing systems attempt to mitigate delta disk growth by redirecting user data and system temporary content to separate disks, and/or allowing the delta disk to revert to checkpoint images when the delta disk grows to a particular size. However, customizing each of the virtual desktops to enable such mitigations is time-consuming. Further, applying the customizations often requires at least two reboot operations that further slow the virtual desktop provisioning process, and negate the benefits of fast instantiation of the virtual desktops. The reboot threats arise, for example, from operations performed on each of the virtual desktops. For example, the first reboot operation may occur when setting a computer name and activating a license. The second reboot operation may occur when joining a domain, performing checkpointing operations, and/or responding to reboot requests from a device manager executing on the virtual desktop (e.g., to install device drivers for added disks).
Performing two full reboot cycles during guest customization of each desktop clone negatively affects performance. In large scale provisioning of thousands of virtual desktops using the existing systems, for example, the reboot cycles aggravate boot storm levels (e.g., a peak surge of memory utilization) which cause elevated input/output operations per second (IOPS) at the storage layer thereby preventing customers from realizing storage savings from the storage consolidation of using linked clone VMs. Additional storage may be purchased, but this only increases cost for the consumer. In addition, when rebooting, each virtual desktop loses the benefit of memory page sharing with a parent virtual machine such that “instant” instantiation is not available.
Further, with the existing systems, the additional time to prepare the virtual desktops increases the overall provisioning time, which may leave the system vulnerable to any transient environment issue thereby increasing the failure rate and cost of ownership by the customer.